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Homework Help: Gravit. rotational energy related to KE

  1. Sep 24, 2008 #1
    "Consider a system of just two particles, with identical masses, orbiting in circles about their center of mass. SHow that the gravitational potential energy of this system is -2 times the total kinetic energy.


    2. Relevant equations
    KE = 1/2 mv^2
    U(potential) = -2U(kinetic)
    grav. potential =
    U=-GMm-r

    3. The attempt at a solution
    we're supposed to set 1/2mv^2 to the rotational gravitational energy -- but I think i have the wrong equation and I don't know where to go from here....
     
  2. jcsd
  3. Sep 24, 2008 #2

    tiny-tim

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    Welcome to PF!

    Hi kate! Welcome to PF! :smile:

    Hint: find the force on each particle, and balance it with the centripetal acceleration to find v. :wink:
     
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